In the construction of a modern building there is an opening for a precast panel. A shell of a building is constructed with openings. Then, there is placed in the openings precast panels.
In an office building, which may vary in height to many stories such as 50 or 75 stories, the shell of the building is constructed with the openings. Then, there is placed in these openings precast panels.
A precast panel may be of various sizes and thickness. An example of a precast panel is a reinforced concrete panel. This reinforced concrete panel may have a height of four feet or five feet and a length of ten feet to fifteen feet. Also, the thickness may vary from eight inches to twelve inches. The reader is to understand that the dimensions of the reinforced concrete panels can vary and are subject to the building and the requirements of the building. A reinforced concrete panel may have a weight of approximately fifteen tons. The manuevering of such a heavy reinforced concrete panel is difficult. Assume, for example, that the openings for receiving the reinforced concrete panel are at the tenth story of the building. It is necessary to lift this panel to the tenth story. Generally, in the construction of a modern high rise building there is a crane. For a building of only a few stories the crane may be on the ground. For a building of many stories the crane is on top of the building. The reader is to understand that as the height of the building increases the crane also is positioned at a higher elevation on the building. In other words, as the building increases in height, the crane positions itself on the top floor or story.
In the construction of a modern concrete and reinforced steel building there are spandrel beams. These spandrel beams are so constructed that the opening for a precast concrete panel may be as much as three feet inside the face of the spandrel beams. In other words, if a precast panel is lifted by a crane and cable, the opening for receiving the precast panel is three feet inside of the spandrel beam and it is difficult to position the precast concrete panel in the opening. A person may question why the opening is not constructed before the spandrel beam is constructed so as to receive the precast concrete panel. In this way the spandrel beam would not interfere with the manuevering and positioning of the precast concrete panel in the opening. From a construction standpoint the spandrel and the floors have to be poured four floors above the point where the opening is for the precast concrete panel. This is necessary as the shoring for the building cannot be removed until the concrete has set to a state where it will support the weight of the floors above the opening. As the spandrels in the floors have to be poured four floors above the opening for the panel the panel could not be inserted until the concrete had cured. By the time the concrete had cured the spandrel was formed and the opening for receiving the precast concrete panel could be inset as much as three feet inside the face of the spandrel beam. The spandrel beam functions as a hindrance to the insertion of the precast concrete panel into the opening in the building.
A normal method of installing a panel of this design in a recessed opening in the building would be to attach lifting rings to the top of the panel. These lifting rings would be attached with coil bolts, and the crane would be hooked to the lifting rings to lift the precast panel to a desired height in the building.
On the precast panel there is an attaching means. The crane has cables which can be attached to the attaching means on the panel. The crane by means of a cable can lift the panel to the proper height in the building under construction. The workers at the opening on the tenth story can grab onto the panel and pull the panel into the opening. Again, the panel may be large and heavy and the workers manually must pull the panel into the opening. The workers in pulling the panel into the opening may be accidently hurt and, unfortunately, may be killed.
In considering some of the problems involved with elevating the precast panels to the tenth floor I consider that proper height of the panel and use as a reference the Y-axis for the height. It is necessary to level the panel so that the panel is horizontal and in this regard I use the X-axis as an indicator of the horizontal levelling of the panel. With respect to the correct position of the precast panel in the opening of the building I use as reference the Z-axis.
The crane can lift the panel to the correct height or the correct position on the Y-axis. Then, the workers can reach out with hooks and sticks and means like that to pull the panel into the openings of the building and this is referred to as moving the panel along the Z-axis. A major problem involved is the levelling of the precast panel so that the panel is horizontal for moving into the openings in the building and the leveling is referred to the X-axis.
The movement of the panel in the Z-axis or in the opening in the building is manually achieved and is difficult. The workers are equipped with poles and hooks for grabbing onto the cables and for pulling the precast panel into the opening. The workers must lean out of the opening to try to grab onto the cable. Again, this introduces the possibility of an accident to the worker in pulling the panel along the Z-axis into the opening of the building. Also, there is introduced the possibility of an accident by trying to level the panel along the X-axis.
It is necessary, after the panel has been pulled into the opening in the building, to position the panel in the opening until the panel can be secured in place. The panel may be secured in place by welding the panels to the structure in the building or by bolting the panel to the structure in the building or by other suitable means.
Some of the shortcomings of the apparatus and method used prior to this invention is a slow process and a time consuming process to position the panel in the opening in the building. As is well known, the workers must be paid for the work of installing the panel in the building and if the process is slow and time consuming then the expense of installing a panel in the building can be a high expense.
Another shortcoming of the method and apparatus for installing a panel in an opening in a building prior to this invention is the possibility of an accident. The worker is working under dangerous conditions and may fall and be seriously hurt or killed. This possibility of an accident is undesirable and, if possible, should be eliminated.
The foregoing method of raising a panel from ground level to an opening on a building under construction consisted of a crane having cables connecting directly to the panels.
The background of the invention has been described with respect to a tenth story of a building under construction. The reader is to understand that in a taller building, say fifty stories or seventy-five stories, the panel can be elevated from ground level to the opening in the building under construction.